Former Arkansas Governor Mike Huckabee backs Mitt Romney's private sector business record while delivering remarks at the RNC.

"To those who question how once-rivals can now be united, it’s quite simple -- we have Barack Obama to thank," said the former 2008 presidential candidate, who sparred with Romney in that year's GOP primaries, in a bid to stir conservatives' passions.

Huckabee passed on running for the Republican presidential nomination a second time in 2012, leaving a void in the primary field this cycle for a visible social conservative like this former Southern Baptist preacher.

It was one of the most direct and pointed speeches targeted at President Barack Obama and it riled up delegates as the convention built towards vice presidential nominee Paul Ryan’s acceptance speech Wednesday night.

"No small differences among us in our party approximate the vast differences between the liberty-limiting, radical left-wing, anti-business, reckless-spending, tax-hiking party of Barack Obama, Harry Reid and Nancy Pelosi, versus an energized America who knows that we can do better," said the former Arkansas governor.

That hard-hitting rhetoric was largely typical of Huckabee's speech, which included jokes about the president's Nobel Peace Prize and Vice President Joe Biden's charitable giving -- along with jabs directed toward a familiar Republican bogeyman, the media.

Huckabee also made reference to his role as a socially conservative leader in an attempt to rally Catholics, a group whom Republicans have courted this cycle, partially by attacking new Obama administration rules about requiring insurers to cover contraception.

"The attack on my Catholic brothers and sisters is an attack on me," he said.

Huckabee made no mention, though, of one of his sharpest differences of late with Republican leaders, over the candidacy of Todd Akin -- the Republican Senate candidate in Missouri whose controversial comments about rape prompted most GOP leaders to call for Akin to end his campaign. Huckabee has stood by and defended Akin.